Hydrogen ion and electrolyte excretion of the single human sweat gland

Summary pH, bicarbonate, sodium, potassium and lactate concentrations were measured in sweat from single human sweat glands.The interpretation of the results is that the gland duct reabsorbs bicarbonate from a bicarbonate-rich precursor fluid by means of proton excretion into the lumen. This process is carbonic anhydrase dependent and acetazolamide-sensitive. Moreover it is speculated, that intact hydrogen excretion may be essential for the reabsorption of sodium and the excretion of potassium by the gland duct.Lactate is excreted in human sweat in high concentrations (range 24 to 10 mMols/l). Within the pH range observed different grades of dissociation of lactate do not contribute significantly to the bicarbonate secretion.From the unaltered lactate concentrations after acetazolamide in final sweat it is concluded that the postulated H-Na-exchange mechanism consumes minimal amounts of energy which can not be detected with the applied method.Supported by Schweizerischer Nationalfonds and National Cystic Fibrosis Research Foundation of U.S.A. (NCFR).